Catheters such as angiographic catheters are generally reinforced with internal tubular reinforcing sleeves which are typically made of woven or otherwise spirally arranged crossing strands, typically made of metal. Such angiographic catheters are currently used in a variety of clinical procedures in which a fluid, particularly x-ray contrast media, is injected through the catheter into a blood vessel of the body leading to and from the heart for use in flush studies and ventriculograms. To accomplish this, angiographic catheters are frequently threaded through the aorta and the heart itself, to pass through the aortic valve for x-ray imaging of the heart ventricle or the like.
Many designs of angiographic catheters are known. However, typically, the currently preferred designs of angiographic catheters for flush studies or ventriculograms are so-called "pigtail" catheters, in which the distal tip of the catheter defines a loop, which facilitates the entry of the distal tip of the catheter through the aortic valve without causing any damage. However, straight catheters may also be used for similar purposes.
Also, as shown for example in Ruiz U.S. Pat. No. 4,573,476, the distal end of an angiographic catheter may define side holes for the lateral outflow of x-ray contrast fluid or the like, along with a longitudinal, distal exit for the catheter lumen, so that this fluid is delivered out of the distal end of the catheter in longitudinal manner.
The purpose of the typically-braided metal strand tubular reinforcing member is to increase the stiffness and strength of the catheter tubular body, to facilitate push-advancement of the catheter through the vascular system of the patient. In the prior art, the braided metal strand tubular reinforcing sleeve is absent from the distal tip area of the catheter where the side holes reside, and is also absent in the pigtail area distal to the side holes. Accordingly, the tip area is of less strength than the main body of the catheter which carries the tubular reinforcing sleeve. As a result of this, complaints have arisen as to some currently available angiographic catheters from surgeons, who have reported that in clinical use, as they have attempted to put the pigtail tip through the aortic valve, the distal tip area in which the side holes reside sometimes buckles. This of course is quite undesirable.
In accordance with this invention, an improved catheter is provided, which may be used as a angiographic catheter, and which reduces or eliminates the buckling problem of the side hole area in the tip. At the same time, the catheter may be manufactured with improved facility and simplicity, resulting in a reduction of the manufacturing cost and the consequent overall cost of the catheter, when compared with previous designs.